Biomedical Engineering Reference
In-Depth Information
NMs are already present in many industrial, household, or cosmetic prod-
ucts, and it seems some of these chemicals will be released and influence
our environment. Agricultural practices are expected to benefit from nano-
technology through improving the efficiency and reduction in pesticide
usage for crop protection [6]. However, only few studies on nanoformula-
tion of pesticides have yet been published [7-9]. Importantly, environmental
exposure may also be an issue at the end of the life cycle of some products.
Therefore, to better understand the possible environmental impacts of NMs,
their life cycle and fate in the environment need to be identified.
Industries of the environmental sector are presently testing NP-based
remediation technologies, for example, the decontamination of groundwater
(nanosized zero-valent iron, among others) [4], and the photocatalytic deg-
radation of air pollutants or the germicidal treatment of wastewater using
nanosized titanium dioxide. Still, crucial information on the environmental
fate of NMs, and on their potential adverse effects individually or in combi-
nation with other common pollutants, is lacking [10].
Several reviews on the environmental behavior and toxicity of NM have
been published recently [4,10-14]. In this chapter, the highlight information
of those reviews, as well as the novel information obtained from various
sources included on the International Council on Nanotechnology Web site
(
http://icon.rice.edu/research.cfm
) are summarized in the present general
overview of the potential ecotoxicity of NMs. This information is useful for
ecological risk assessment. The assessment of the environmental impact of
NMs has recently emerged as a serious issue since many of these NMs will
likely enter the environment and subsequently affect environmental and
human health.
10.2 Sources and Exposure to Nanomaterials
To understand the environmental health risks posed by NMs, one should
know how the NMs can reach target organisms in the environment. Several
aspects such as product life cycle, fate, and transport of NMs were described
for human exposure in previous chapters. This information may also apply
to ecological receptors with the exposure difference, which may occur
through water column, groundwater, sediments and soil, depending on the
target organism [16].
Water in the aqueous environment may be considered as a transport
medium or a temporary reservoir because of the tendency of NM to agglom-
erate and precipitate out of solution (or of dispersion). Aquatic receptors, such
as fish and invertebrates, and filter-feeding animals (benthos) are the most
likely targets of NM in the aquatic and benthic media, respectively [1,14-16].
Unfortunately, few toxicity assays have been conducted using sediments.
